# Copyright (c) 2018, Oracle and/or its affiliates.

#

# The Universal Permissive License (UPL), Version 1.0

#

# Subject to the condition set forth below, permission is hereby granted to any

# person obtaining a copy of this software, associated documentation and/or data

# (collectively the "Software"), free of charge and under any and all copyright

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# licensable by each licensor hereunder covering either (i) the unmodified

# Software as contributed to or provided by such licensor, or (ii) the Larger

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# (a) the Software, and

# (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if

# one is included with the Software (each a "Larger Work" to which the

# Software is contributed by such licensors),

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# without restriction, including without limitation the rights to copy, create

# derivative works of, display, perform, and distribute the Software and make,

# use, sell, offer for sale, import, export, have made, and have sold the

# Software and the Larger Work(s), and to sublicense the foregoing rights on

# either these or other terms.

#

# This license is subject to the following condition:

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# The above copyright notice and either this complete permission notice or at a

# minimum a reference to the UPL must be included in all copies or substantial

# portions of the Software.

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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

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import sys

# copied from: types.py#new_class

# Provide a PEP 3115 compliant mechanism for class creation

def new_class(name, bases=(), kwds=None, exec_body=None):

"""Create a class object dynamically using the appropriate metaclass."""

meta, ns, kwds = prepare_class(name, bases, kwds)

if exec_body is not None:

exec_body(ns)

return meta(name, bases, ns, **kwds)

def prepare_class(name, bases=(), kwds=None):

"""Call the __prepare__ method of the appropriate metaclass.

Returns (metaclass, namespace, kwds) as a 3-tuple

*metaclass* is the appropriate metaclass

*namespace* is the prepared class namespace

*kwds* is an updated copy of the passed in kwds argument with any

'metaclass' entry removed. If no kwds argument is passed in, this will

be an empty dict.

"""

if kwds is None:

kwds = {}

else:

kwds = dict(kwds) # Don't alter the provided mapping

if 'metaclass' in kwds:

meta = kwds.pop('metaclass')

else:

if bases:

meta = type(bases[0])

else:

meta = type

if isinstance(meta, type):

# when meta is a type, we first determine the most-derived metaclass

# instead of invoking the initial candidate directly

meta = _calculate_meta(meta, bases)

if hasattr(meta, '__prepare__'):

ns = meta.__prepare__(name, bases, **kwds)

else:

ns = {}

return meta, ns, kwds

def _calculate_meta(meta, bases):

"""Calculate the most derived metaclass."""

winner = meta

for base in bases:

base_meta = type(base)

if issubclass(winner, base_meta):

continue

if issubclass(base_meta, winner):

winner = base_meta

continue

# else:

raise TypeError("metaclass conflict: "

"the metaclass of a derived class "

"must be a (non-strict) subclass "

"of the metaclasses of all its bases")

return winner

# This will re-define the __build_class__ defined in functions.py

def __build_class__(func, name, *bases, **kwargs):

"""

__build_class__(func, name, *bases, metaclass=None, **kwds) -> class

Internal helper function used by the class statement.");

see: https://github.com/python/cpython/blob/36c1d1f1e52ba54007cbecb42c5599e5ff62aa52/Python/bltinmodule.c#L51

"""

if not hasattr(func, "__call__"):

raise TypeError("__build_class__: func must be a function")

if not isinstance(name, str):

raise TypeError("__build_class__: name is not a string")

return new_class(name, bases=bases, kwds=kwargs, exec_body=func)

sys.modules['builtins'].__build_class__ = __build_class__